The present invention generally relates to the testing of integrated circuit (IC) devices, and has particular application to the testing of optical IC devices where the IC must be illuminated by a light source to produce a detectable electrical response for test.
The testing of IC devices is typically accomplished using IC test sockets which hold a device under test ("DUT") to a test board (often referred to as a "DUT board") with the electrical contacts of the IC facing the DUT board. This orientation of the DUT is known as a "live bug" orientation referring to its resemblance to a live bug with its feet on the ground. While conventional IC socket designs are well adapted to the testing in a live bug orientation, a need exists for an IC socket which can accomplish a test of an IC in a "dead bug" orientation where the IC leads are reversed in the test cavity, that is, where the IC is on its back with its contacts facing up away from the DUT board . One class of IC devices that are best suited for testing in a dead bug orientation are optical IC devices having photoactive circuitry that must be illuminated to produce an electrical signal capable of being processed. Such optical ICs are used in a variety of applications ranging from optical sensors to digital cameras. When testing such ICs ("optical DUTs") the photoactive circuitry of the optical DUT must be illuminated to produce a test result. Where automated pick and place machinery is used to load the test socket, an optical DUT cannot be easily illuminated since the photoactive circuitry is on the side of the DUT which is picked up by the pick and place arm of the automated handling equipment. Illumination from the side of the DUT would require a costly mechanism for doing so built into the automated handler.
The present invention provides a test socket and mechanism for efficiently testing a DUT in a dead bug orientation, and particularly for testing the optical DUT in a manner that facilitates illumination of the photoactive circuitry of the optical DUT during test. In accordance with the invention, the optical DUT can be illuminated from the light source below the DUT board, thereby allowing illumination of the DUT from below the DUT board without costly design modifications to the automated handler machinery.